数据库编程

main( int arg, char * args[]) { MYSQL * connection, mysql; mysql_init( & mysql); connection = mysql_real_connect(&mysql, " localhost " , " dbuser1 " , " dbuser1 " , " db1 " , 0 , 0 , 0 ); if (connect == NULL) { printf(mysql_error( & mysql)); return EXIT_FAILURE; } mysql_close(connection); return EXIT_SUCCESS; }

 

执行SQL语句

int mysql_query(MYSQL *pmysql,const char *sql);

参数pmysql是连接到MySQL的指针。 参数sql是要执行的SQL语句。 成功返回0,失败返回非0。     插入数据例子

 int  main( int  arg,  char  * args[])
{
    MYSQL  * connection, mysql;
    mysql_init( & mysql);
    connection  = mysql_real_connect(&mysql,  "  localhost  " ,  "  dbuser  " ,  "  dbuser  " ,  "  db1  " , 0 , 0 , 0  );
      if  (connect ==  NULL)
    {
        printf(mysql_error( & mysql));
          return   EXIT_FAILURE;
    }
      int  state = mysql_query(connection,  "  INSERT INTO table1 (NAME,SEX,AGE,CLASS) VALUES (‘HAHA‘,1,30,‘666‘)  "  );
      if  (state !=  0  )
    {
        printf(mysql_error(connection));
          return   EXIT_FAILURE;
    }
    mysql_close(connection);
      return   EXIT_SUCCESS;
} 

 

修改数据例子

 int  main( int  arg,  char  * args[])
{
    MYSQL  * connection, mysql;
    mysql_init( & mysql);
    connection  = mysql_real_connect(&mysql,  "  localhost  " ,  "  dbuser1  " ,  "  dbuser1  " ,  "  db1  " , 0 , 0 , 0  );
      if  (connect ==  NULL)
    {
        printf(mysql_error( & mysql));
          return   EXIT_FAILURE;
    }
      int  state = mysql_query(connection,  "  UPDATE table1 SET CLASS = ‘250‘ WHERE NAME = ‘HAHA‘  "  );
      if  (state !=  0  )
    {
        printf(mysql_error(connection));
          return   EXIT_FAILURE;
    }
    mysql_close(connection);
      return   EXIT_SUCCESS;
} 

 

删除数据例子

 int  main( int  arg,  char  * args[])
{
    MYSQL  * connection, mysql;
    mysql_init( & mysql);
    connection  = mysql_real_connect(&mysql,  "  localhost  " ,  "  dbuser1  " ,  "  dbuser1  " ,  "  db1  " , 0 , 0 , 0  );
      if  (connect ==  NULL)
    {
        printf(mysql_error( & mysql));
          return   EXIT_FAILURE;
    }
      int  state = mysql_query(connection, [DELETE FROM table1 WHERE NAME =  ‘  HAHA  ‘"  ); 
     if  (state !=  0  )
    {
        printf(mysql_error(connection));
          return   EXIT_FAILURE;
    }
    mysql_close(connection);
      return   EXIT_SUCCESS;
} 

 

执行SELECT语句得到查询结果

MYSQL_RES *mysql_store_result(MYSQL *pmysql);

成功返回一个查询结果指针，查询无结果或者错误返回NULL。

mysql_free_result(MYSQL_RES *res)

调用完mysql_store_result，一定要用mysql_free_result释放相关的资源。   查看查询结果

MYSQL_ROW mysql_fetch_row(MYSQL_RES *result);

例子

while(row = mysql_fetch_row(result)) != NULL)

{

  printf([name:%s,sex:%s,age:%s,class:%s\n],row[0], row[1], row[2],row[3]

}

尽管在表中age是数字，但mysql返回的只不过是以NULL结尾的字符串。   查看查询结果中的字段信息

MYSQL_FIELD *mysql_fetch_field (MYSQL_RES *result);

例子

  while ((sqlField = mysql_fetch_field(result)) != NULL)

  {

  printf("%s\n", sqlField->name);

  }

 

执行SELECT例子1

 int  main( int  arg,  char  * args[])
{
    MYSQL  * connection, mysql;
    mysql_init( & mysql);
    connection  = mysql_real_connect(&mysql,  "  localhost  " ,  "  dbuser1  " ,  "  dbuser1  " ,  "  db1  " , 0 , 0 , 0  );
      if  (connect ==  NULL)
    {
        printf(mysql_error( & mysql));
          return   EXIT_FAILURE;
    }

      int  state = mysql_query(connection,  "  SELECT NAME,SEX,AGE,CLASS FROM table1  "  );
      if  (state !=  0  )
    {
        printf(mysql_error(connection));
          return   EXIT_FAILURE;
    }

    MYSQL_RES  *result =  mysql_store_result(connection);
      if  (result == (MYSQL_RES * )NULL)
    {
        printf(mysql_error(connection));
          return   EXIT_FAILURE;
    }

    MYSQL_ROW row;
      while ((row = mysql_fetch_row(result)) !=  NULL)
    {
        printf(  "  name %s, sex %s, age %s, class %s\n  "  ,
                row[  0 ],row[ 1 ],row[ 2 ],row[ 3  ]);
    }
    mysql_free_result(result);
    mysql_close(connection);
      return   EXIT_SUCCESS;
} 

 

执行SELECT例子2

 int  main( int  arg,  char  * args[])
{
      if  (arg <  5  )
          return   0  ;

    MYSQL  * connection, mysql;
    mysql_init( & mysql);
    connection  = mysql_real_connect(&mysql, args[ 1 ], args[ 2 ], args[ 3 ], args[ 4  ],
              0 ,  0 ,  0  );
      if  (connection ==  NULL)
    {
        printf(  "  %s\n  " , mysql_error(& mysql));
          return   EXIT_FAILURE;
    }
    printf(  "  success connect to mysql\n  "  );
      int  state = mysql_query(connection,  "  SET NAMES utf8  "  );

      char  buf[ 1024  ];
      while  ( 1  )
    {
        memset(buf,   0 ,  sizeof  (buf));
        read(STDIN_FILENO, buf,   sizeof  (buf));
          if  (strncmp(buf,  "  exit  " ,  4 ) ==  0  )
        {
              break  ;
        }
        state  =  mysql_query(connection, buf);
          if  (state !=  0  )
        {
            printf(  "  %s\n  "  , mysql_error(connection));
        }

        MYSQL_RES  *result =  mysql_store_result(connection);
          if  (result ==  NULL)
        {
            printf(  "  %s\n  "  , mysql_error(connection));
              break  ;
        }

        MYSQL_FIELD  * sqlField;
          int  iFieldCount =  0  ;
          while  ((sqlField = mysql_fetch_field(result)) !=  NULL)
        {
            printf(  "  %s\t  " , sqlField-> name);
            iFieldCount ++ ;
        }
        printf(  "  \n  "  );

        MYSQL_ROW row;
          while  ((row = mysql_fetch_row(result)) !=  NULL)
        {
              int   i;
              for  (i =  0 ; i < iFieldCount; i++ )
            {
                printf(  "  %s\t  "  , row[i]);
            }
            printf(  "  \n  "  );
        }
        mysql_free_result(result);
    }
    mysql_close(connection);
      return   EXIT_SUCCESS;
} 

 

断开连接

mysql_close(MYSQL *connect);

使用完数据库后要记得断开连接，释放相关资源。   复制去Google翻译 翻译结果  

数据库编程

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